Systematic Variation of Friction of Rods

Who is working on this project: Dezhong Tong

In settings from shipping to sailing to surgery, thousands of different types of knots are used every day, each requiring a specific amount of force to tighten. This force depends on the material properties, friction, and the topology of the knot. A knot typically also has a load-bearing capacity; force beyond this level causes the knot to be undone, and excessive force may result in material failure in the knot. Moreover, some knots hold tight without any external force while others easily get untangled. In other words, the knots can store energy in the material. This concept is called a topological battery with implications in nanometer-sized knots in DNA to macroscopic knots in structural engineering.

The research objective of this project is to quantify the mechanical response of knots tied in elastic rods. The project will employ (1) fast numerical simulations inspired by computer graphics, (2) innovative materials with customizable friction, and (3) autonomous robotic experiments to untangle the mechanics of knots.

Funding: This research was funded by the National Science Foundation (Award # CMMI-2101751 and CMMI-2101745). M.K.J. and D.T. also acknowledge support from the National Science Foundation (Award # IIS-1925360).

Publication: Khalil, M., Tong, D., Wang, G., Jawed, M. K., and Khoda, B. "Systematic Variation of Friction of Rods." Journal of Applied Mechanics (2022) [LINK]

YouTube: https://www.youtube.com/watch?v=0ZqY2dDNJRM